1. Technical Field
This invention relates generally to water craft and rudder/steering devices. More particularly, the invention relates to self-deploying rudder devices which respond to fluid flow pressure, such as that provided by the exhaust from jet-propelled water craft.
2. History of Related Art
Jet-propelled water craft are typically designed to be steered using exhaust fluid flow pressure developed from a movable jet nozzle submerged below the surface of the water. However, as the throttle-controlled thrust is retarded, the ability to steer is substantially reduced. In fact, since most jet-propelled water craft have no rudders, any type of substantial reduction in exhaust pressure, coupled with a steering capability that depends upon a steerable exhaust nozzle, typically makes it impossible to steer such water craft effectively.
Various mechanisms have been developed to provide alternative steering capability for jet-propelled water craft. However, such mechanisms have many shortcomings. For example, some rudder mechanisms require manual operation to deploy into the water, or to be removed from the water. Spring-biased rudder mechanisms, while providing the ability to displace upwardly upon contact with foreign objects, typically remain in the water at all times, producing excessive drag during high-speed operation of the water craft. Finally, some of these mechanisms are designed to deploy automatically, but when stored, trail behind the water craft above the water line. Thus, such devices present a significant safety hazard to anyone falling off of the water craft during use.
Other attempts to deal with the problem of providing slow speed steering control to jet-powered water craft in a safe and efficient manner include the use of a third class lever connected to a rudder, which pivots from the uppermost portion of the lever, where it is attached to the jet nozzle. Thus, the rudder extends behind the craft for some distance while deployed in the steering position, and extends both behind the craft and above the water line while in the stowed, or xe2x80x9crunningxe2x80x9d mode. Such operational characteristics present a significant hazard to any operator, or passenger of the water craft that falls to the rear of the craft during operation. Further, re-boarding of the craft after a fall is quite difficult if the rudder apparatus projects into the path of the boarding operator and/or passenger.
Such devices do not allow for adjustments in the level of thrust required to deploy and/or store the rudder based on the exhaust pressure developed at idle speed, nor do such devices allow for raising the rudder completely out of the way for beaching/launching the water craft. Finally, such devices do not provide any type of stabilizing force for the stored rudder blade during powered operation.
Thus, what is needed is a rudder assembly for use with an exhaust port which operates to automatically deploy the rudder below a selected exhaust thrust level and which operates automatically to store the rudder when the thrust level is above the preselected level. Of course, such a device would be even more useful if it provided the option for manual deployment and storage. Finally, such a device would be most useful if automatic operation could be adjusted to occur at some variable level of thrust, selected by the user.
The self-deploying rudder assembly of the present invention includes a mounting assembly which attaches to an outlet nozzle, or exhaust port, such as those used on jet-propelled water craft. The self-deploying rudder assembly also includes a thrust plate, rudder shaft, and rudder blade, which are typically integrated into a single unit called the rudder blade assembly. The rudder blade attaches to one end of the rudder shaft, and the thrust plate attaches to the other end. The shaft typically operates as a first class lever, having a rudder pivot point, or fulcrum, located between the thrust plate and the rudder blade. A deployment means, such as a spring, is attached to the shaft and the mounting assembly so as to bias the rudder blade in a downward, fully-deployed position, to allow steering the water craft at low levels of thrust. The thrust plate intercepts the exhaust from the exhaust port and operates to urge the rudder blade into a stored position when the thrust level selected by the operator of the water craft is above some preselected thrust level. That is, when the water craft operator increases the amount of throttle to the jet, so the craft moves forward at high speed, the rudder blade will be stored underneath the water craft, typically in a grooved skeg. However, when the throttle is rolled off and the water craft is operated at a low speed, the rudder will be deployed (using the deployment means) into an operative position. The thrust plate may include an adjustable cross-sectional surface area, or an orifice, which allows selection of the low speed threshold for rudder deployment and storage.
An alternative embodiment of the invention divides the rudder shaft into two portions, an upper shaft and a lower shaft. The upper shaft engages the lower shaft in a continuous fashion using a gear attached to each of the shafts, such that the upper shaft and an attached or integral gear is continuously engaged with a lower shaft gear, which is integral with, or attached to, the lower shaft. Alternatively, a pushrod assembly can be attached to the upper and lower shafts so that movement out of the exhaust stream by the upper shaft causes direct movement and storage of the lower shaft and rudder blade. In this case, the rudder shaft no longer operates as a first class lever; however, all of the other advantages of the invention are retained. In addition, at high operating speeds, the rudder blade folds toward the rear of the craft for storage. This allows the fluid forces exerted against the rudder blade during high speed operations to assist retention of the rudder blade when it is stored within the grooved skeg.
As a matter of increased utility, the self-deploying rudder assembly may incorporate a cable or other storage means which allows storage of the rudder unit for beaching and/or launching the water craft. The rudder assembly may also include a rotatable gear engaged to a gear rack which rotates the rudder blade as it moves toward a stored position such that the rudder blade is stored flush, and in the same plane, as the undersurface of the water craft hull.
Dual-shaft, rudder blade combinations can also be used. The use of additional rudder blade area, such as may occur with dual rudders, increases the ability to steer the water craft during conditions of low or no thrust.